A type of security seal commonly known as a "ball seal" is widely used to seal the doors of railroad freight cars, trucks and other containers. Such seals comprise a metal housing with a metal strap shackle having one end secured to the housing. The other end of the shackle is insertable into a housing aperture into locking engagement with suitable internal means.
Although such seals are widely used, improvements in reliability and tamper resistance are always desirable. Also, it has been found that some seal users would prefer to provide their own shackles, and apply their own identification numbers, for greater security, which is not possible at present since one end of the shackle is permanently attached to the seal body. Numbering of such seals is generally a time consuming hand operation.